The Large Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator. It was built by the European Organization for Nuclear Research (CERN) from 1998 to 2008, with the aim of allowing physicists to test the predictions of different theories of particle physics andhigh-energy physics, and particularly that of the existence of the hypothesized Higgs boson[1] and of the large family of new particles predicted bysupersymmetry.[2] The LHC is expected to address some of the most fundamental questions of physics, advancing the understanding of the deepest laws of nature. It contains six detectors each designed for specific kinds of exploration.
The LHC lies in a tunnel 27 kilometres (17 mi) in circumference, as deep as 175 metres (574 ft) beneath the Franco-Swiss border near Geneva,Switzerland. Its synchrotron is designed to collide opposing particle beams of either protons at up to 7 teraelectronvolts (7 TeV or 1.12 microjoules) per nucleon, or lead nuclei at an energy of 574 TeV (92.0 µJ) per nucleus (2.76 TeV per nucleon-pair).[3][4] It was built in collaboration with over 10,000 scientists and engineers from over 100 countries, as well as hundreds of universities and laboratories.[5]
On 10 September 2008, the proton beams were successfully circulated in the main ring of the LHC for the first time,[6] but 9 days later operations were halted due to a magnet quench incident resulting from an electrical fault. The ensuing helium gas explosion damaged over 50superconducting magnets and their mountings, and contaminated the vacuum pipe.[7][8] On 20 November 2009 proton beams were successfully circulated again,[9][10] with the first recorded proton–proton collisions occurring 3 days later at the injection energy of 450 GeV per beam.[11] On 30 March 2010, the first collisions took place between two 3.5 TeV beams, setting the current world record for the highest-energy man-made particle collisions,[12] and the LHC began its planned research program.
The LHC will operate at 4 TeV per beam until the end of 2012, 0.5 TeV higher than in 2010 and 2011. It will then go into shutdown for 20 months for upgrades to allow full energy operation (7 TeV per beam), with reopening planned for late 2014.[13]
 | |
| LHC experiments | |
|---|---|
| ATLAS | A Toroidal LHC Apparatus |
| CMS | Compact Muon Solenoid |
| LHCb | LHC-beauty |
| ALICE | A Large Ion Collider Experiment |
| TOTEM | Total Cross Section, Elastic Scattering and Diffraction Dissociation |
| LHCf | LHC-forward |
| MoEDAL | Monopole and Exotics Detector At the LHC |
| LHC preaccelerators | |
| p and Pb | Linear accelerators for protons(Linac 2) and Lead (Linac 3) |
| (not marked) | Proton Synchrotron Booster |
| PS | Proton Synchrotron |
| SPS | Super Proton Synchrotron |
| Intersecting Storage Rings | CERN, 1971–1984 |
|---|---|
| Super Proton Synchrotron | CERN, 1981–1984 |
| ISABELLE | BNL, cancelled in 1983 |
| Tevatron | Fermilab, 1987–2011 |
| Relativistic Heavy Ion Collider | BNL, 2000–present |
| Superconducting Super Collider | Cancelled in 1993 |
| Large Hadron Collider | CERN, 2009–present |
| Super Large Hadron Collider | Proposed, CERN, 2019– |
| Very Large Hadron Collider | Theoretical |
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